Major Discovery Raises Prospect of Better Patient Care By Improving
Platelet Life Span

MELBOURNE, Australia, March 23, 2007 /PRNewswire/ -- Scientists
at WEHI have made a discovery with potentially profound
implications for the care of patients, especially those undergoing
cancer chemotherapy.

The research team led by Drs Benjamin Kile and David Huang has
discovered that platelet life span is controlled by two key
molecules. The discovery raises the prospect of developing a new
drug to prolong the life span of platelets stored in blood banks,
effectively increasing the availability of this life-saving blood
product.

An undesirable side effect of cancer chemotherapy is extensive
bruising and potentially life-threatening bleeding. This is caused
by the unintended depletion of platelets, tiny circulating blood
cells that are essential for blood clotting and wound healing.
Consequently, the well being of some patients depends upon platelet
transfusions, particularly during the vulnerable periods that
follow anti-cancer treatment. The significant demand for high
quality platelets, coupled with their short shelf life of only five
days, presents major logistical challenges in clinical
practice.

The scientific team has found that two specialised molecules act
in opposition to each other to control platelet life span by
regulating the process known as "apoptosis." This term refers to
the normal and healthy self destruction of old, damaged and surplus
cells. One protein (known as Bcl-xL) acts to preserve the life of
the platelet, while the other protein (Bak) prepares the cell to
self-destruct after its usual life span within the body - - about a
week.

WEHI's Dr David Huang said, "Apoptosis is an essential process,
common in other cells, but the central role it plays in controlling
the life span of the highly specialised platelet has not been
previously appreciated. With this new knowledge, we are in a much
stronger position to devise better therapies for the management of
platelet-related diseases."

Dr Kile added, "For fifty years doctors have speculated about
what controls platelet life span. We now know the identity of the
precise molecular switch responsible. The team is now actively
pursuing a drug development program aimed at manipulating this
switch in order to prolong the life span of blood bank platelets,
increasing their availability to patients receiving cancer
treatment and others in danger of serious bleeding".

At the opposite end of the scale, shortening platelet life span
may be useful in the treatment of other diseases. For instance, too
many platelets can trigger dangerous blood clots leading to strokes
or heart attacks. Reducing platelet life span may therefore prove
valuable in the prevention and management of these life-threatening
conditions.

The scientific research was generously funded by the Australian
National Health and Medical Research Council (NHMRC); the State
Government of Victoria (DIIRD); the Australian Research Council
(ARC); the Australian Cancer Research Foundation (ACRF); the Cancer
Council of Victoria (CCV); the National Cancer Institute (US); the
US-based Leukemia and Lymphoma Society (www.lls.org); and MuriGen Pty Ltd
(www.murigen.com.au), a company
based at the WEHI Biotechnology Centre in Bundoora, Victoria.